Art or method of treating slimes.



n. COLE. ART 0R METHOD OF TREATING SLIMES.

w 1 1 n Wm NH H Ms =3 m AM a D APPLICATION HILED APR. 12. I9I3.

INVEIVTOR WITNES S D. COLE;

ART 0R METHOD OF TREATING SLIMES.

APPLICATION FILED APR. 12. 19.13.

1,205,326. Patented Nov. 21, 1916.

3 SHEETS-SHEET 2.

fie. 5,

WITNESSES D. COLE.

ART 0R METHOD OF TREATING SLIMES.

arrucmmn men APR. 12, 1913.

1,265,326, Patented Nov. 21, 1916.

3 SHEETSSIIEET 3.

" En era DAVID COLE, OF TUCSON, ARIZONA.

ART OR METHOD OF TREATING SLIMES.

I J \J u mosses.

I To all whom it concern:

Be it known that I, DAVID COLE, a citizen of the United States, residingat Tucson, in the'county of Pima-and State of Arizona, have inventedcertain new and useful Improvements in the Art or Method of TreatingSlimes, of which the following is a specification. a

This invention relates to an art or method of classifying-andconcentrating slimes, particularly adapted tojthe treatment of sulficopper ores and similar ores. e

The apparatus hereinafter described for practising this process formsthe subject of,

volved in the invention may be fully under dled in all cases in whichthe metallic elements to be recovered are so disseminated throughout theore as to require fine grinding. The difliculty in handling such slimesarises from the presence in them of a large percentage of what have cometo be known in the art as colloids, as contradistinguished fromcrystalloids or crystalline metallic sulfids and other generallycrystalline metallic compounds. As a general rule the so-called colloidscontain a relatively small percentage of metallic values in sulfid formand their presence always greatly hinders the concentration of suchvalues from the crystalline material because of acharacteristic'flocculent arrangement which the colloids assume almostas soon as the slime solution comes to rest and solids begin to settle.

By 'a careful series of tests I have determined the characteristicbehavior ofsuch slimes during the settling action. When theSpecification of Iietter s ratent.

have had an opportunity .to assume their flocculent arrangement, thesettling of the crystalhne particles isvery little impeded by thecolloids, and takesplace rapidly, so

that a small percentage 'of the crystalloids, generally thelargerparticle's, readily settle to the bottom; As the colloids assume theircharacteristic flocoulent form the'flakes be-' gin to arrest and sustainthe smaller crystalloid particles, and as the flocculence becomes morepronounced and the flakes settle into closer contact with one another,larger and larger crystalloid particles are arrested. This settling ofthe flakes takes place slowly, because 1 ofthe retarded outflow of waterfrom between the flakes, but by the time it has progressed to a point atwhich the solids form about 7% of the mixture the settling of thecrystalloids is greatly impeded and by the time the solids form 10% ofthe mixture all settling of the crystalloids through the flocculentcolloids seems to cease. In all types of cones, spitzkastens and otherprior devices used in treating this class of material, 'much thickeningof the solution by settling of the flocculent colloids necessarily takesplace prior to the settling out of a largefpercentage of thecrystalloids and as the solution is of considerable depth in these priordevices an unduly large proportion of concentratable crystalloids doesnot reach the bottom and separate but remains mixed with and goes withthe c0lloids. The tests have further shown that if the slime solution besufficiently dilute the settling of the crystalloids is practicallyunimpeded because of the separation of the colloid flakes, thus leavingavenuesbetween them through which the crystalloids may fall, though asthe flakes settle a degree of concentration will ultimately be reachedsufiicientto obstruct the complete precipitation of the crystalloids.

The above considerations have suggested to me the impracticability ofsuccessfully concentrating slimes containing colloids by the presentpractice of thickening the slime prior to feeding it to slimers and thelike; and have suggested the desirability of effecting a preliminaryseparation and removal of the colloids by taking advantage of the earlyportionof the settling cycle of the slime in Patented Nov. 21i, 11916.Application filed-April 12, 1913. Serial No. 760,702.

settling-first begins,' and before the colloids the presence of anexcess of water in very shallow vessels.

If the above principles are to be availed of it is desirable that thepath of the settling particles may be short so that the crystallineparticles may reach the point of removal before the colloid flakes haveseizedthem in the rapidly condensing mass. It is also desirable that thecolloid mass be removed separately thus leaving a comparatively largepercentage of clarified Water to be again used as such.

I have successfully carried out my process by making use of, a largesettling tank approximately six inches deep to which I feed a diluteslime mixture, for example one containing about 5% of combinedcrystalloid and colloid solids. The mixture is fed in at one side of thetank, flows slowly across the tank and is discharged over a wide shallowoverflow at the opposite side of the tank. The movement of the slimeacross the tank is characterized generally by a whole flow ascontradistinguished from a surface flow.

The shallowness of the tank and the dilute nature of the solution causea settling out of the crystalloids early in the path of the solutionacross the tank, the colloids being carried farther across the tankbecause of their greater tendency to remain in suspension.

Various slightly different methods of availing of the broadcharacteristic principle of my invention have been ,used by me, the mostsatisfactory involving a repetition of the settling process to secure abetter separation and incidentally to recover a pro- 7 portion of thewater used in the process.

The simplest method is of course to make use of a relatively narrow tankwith a correspondingly small number of belts, suflicient to include thezone of settling of the crystalloids and usually a limited portion ofthe zone in which mixed crystalloids and colloids are precipitated. Thebulk of the colloids thus overflow from the tank as tailings with thewater, the precipitated material being the concentrates. In order tosave part of the water it is preferable however to make use of a muchwider tank having a correspondingly larger number of belts, the tankbeing so designed-that all the solids both crystalloid and colloid aresuccessively precipitated and clear water is discharged at the overflow.The belts will then lie in three zones (1) that in which, practicallyonly crystalloids are precipitated, (2) that in which substantialproportions of both crystalloids and colloids are precipitated, and (3)that in which practically only colloids are precipitated. The difierentclasses of material are thus removed from the tank by three differentsets of belts, and may then be individually treated.

To secure a practical elimination of colloids the water discharged atthe overflow is fed together with the .precipitates from zones 1 and 2to a second and narrower tank. Because of the dilute nature of thesolution, complete precipitation takes place in this tank 'and clearwater overflows, and there is a relatively well defined .line bteweenthe zones of precipitation of colloids and of crystalloids, which areconsequently carried out by different sets of belts.

.The crystalloid material freed of colloids by any of the above methodsis readily treated with a better recovery of values by concentratingmethods well known in the art. If the colloid material contains mineralvalues it may be subjected to appropriate subsequent treatment torecover them, such as flotation processes, or chemical leaching.

I shall now describe my method or process in detail with reference tothe device which has proved successful as a means of performing it. Irecognize, however, that other devices are available to effect thecarrying out of the'process and do not limit myself to this particulardevice or to the'exact arrangements shown.-

In the accompanying drawings: Figure 1 is a section through a settlingtank embody- 1 ing my invention, the plane of section being taken on thehue 1-1 of Fig. 2; Fig. 2 is an elevation of the right end of the samelookfrom the supply side; Fig. 5 is a plan view of the tank showing thegeneral arrangement of the belts, location of the supply and overflow,etc; Fig. 6 is a flow diagram of the simplest method of practising myinvention; Fig. 7 is a flow diagram of the preferred method ofpractising my invention; and Fig. 8 is a fragmentary vertical section ofa modified form of settling tank. Y

Referring to the drawings, it will be noted that the settling tankproper consists of a bottom or floor 1 flat at its middle portion andgradually sloping upward toward the ends. The sides of the tank 2 areprovided with the supply or inlet chamber or enlargement 3 and a sideoverflow 4 located at a slight distance below the top of the side walls2 in order that material may flow from the tank in a wide thin sheet.The arrangementof the sides 2, overflow 4 and of the bottom 1 are suchthat the maximum depth Running longitudinally in the tank are aplurality of rubber-coated belts 5 the lower sides of the first twobelts in the series being preferably formed with the V-shaped ribs orflights 6. The function of these flights is to move toward the edge ofthe belt any relatively coarse material which may find its way beneaththe same so that the belts will not be lifted away-from the bottom ofthe tank by the accumulation of material beneath them. The belts arearranged in pairs, successivepairs being driven in opposite directions.Each belt runs at one end on a live drum or pulley 7 and at the oppositeend on an idle drum or pulley 8, the return run of the belt' beingguided by snub pulleys 9 through a shallow water basin 10 designed toclean and prevent unduewear in the belts. The spray pipes 11 areprovided to wash material off the belts as they leave the, live pulleysso as to prevent the belts from carrying any solid material on thereturn run. The live pulleys 7 are mounted in the hoppers or boxes 12adapted to receive any solid material conveyed out of the tank by thebelts, and discharge it through openings 13 into suitable troughs orlaunders indicated at 14. The arrangement of these launders varies withthe particular case as is obvious. Each pair of adjacent live pulleys isdriven by a sprocket l5 interposed between them. This is connected'bymeans of a chain 16 to a suitable speed reducing train 17 shown asconsisting of gears and sprockets. take any of many well known forms. Areducing train 17 is preferably provided for each sprocket 15, or inother words for each pair of belts if necessary, and each reducing ,Thedimensions given are only illustrative identical therewith in form andfunction.

See Fig. 8. Thus a double machine is formed without increase in floorspace and with only moderate increase in height. However, it isnecessary in the case of the lower belt to provide a squeegee 22 setuponv the'belt and lubricated with water from a spray pipe 23 for thepurpose of removing the material brought up to this point by the Itmight train receives its power from one of the line shafts 18 throughsuitable individual change speed devices indicated at 19. The lineshafts are driven by motors such as the electric motors indicated bydotted lines at 20. The speed of movement of each pair of belts may besubjected to individual regulation,

by means of the change speed devices 19.

The purpose of arranging the alternate pairs of belts to run in oppositedirections is to neutralize the eflect of the moving belts upon the flowof material across the tank. Obviously they might all be run in the samedirection but I prefer the arrangement described. Although thedimensions of the tank and belts are subject to considerable variation Ihave secured very satisfactory results with a tank in which the beltstravel about 35 feet under the surface of material in the tank, thebelts moving at a speed of about 35 feet per minute. The width of eachpair of belts in this device is approximately 50 inches and the numberof pairs of belts used, and the depth of the .tank, are dependent uponthe nature of the material to be handled and the time required to complete the cycle desired and the method of treatment adopted as alreadysuggested.

belt. This squeegee effect is produced by applying a piece of thinrubber or a piece of rubber belting upon the smooth surface of,

the belt at an angle with its travel so that the material carried on itssurface is caused to flow off to one side of the belt and be depass outof the spout 13 in the same manner and condition as the product producedon the belt. emerging from the upper basin. Where a large tonnage is tobe handled this arrangement economizes space and is desirable.

As already suggested the principle involved in the process and theapparatus illustrated for practising it, may be utilized in a number ofrelations differing in detail but fundamentally similar.

In Fig. 6 I illustrate diagrammatically a single tank A having eight"belts. The feed from the mill enters at B. The tailings (colloids)overflow at C with the water. The concentrates (crystalloids) areprecipitated and are carried out by the belts (here assumed all to movein the same direction for ease in making the diagram). The concentratesfrom different groups of belts are fed to different clean up machines D,E, F, each of which may, if desired, be particularly adapted'to theclass of material precipitated on the corresponding belts in the tank.

In Fig. 7 I illustrate diagrammatically a sixteen belt tank G. The feedfrom the mill enters at H. Clear Water overflows at I. The first sixbelts discharge crystalloids at J; the next five belts dischargecrystalloids and colloids in varying proportions at K; and the last fivebelts discharge colloid tailings at L. The water overflowing at I andthe solid material from J and K are fed to a six belt tank M and N.Clear water overflows at O and may be used in any desired manner. Thefirst belt discharges at P, the second at and the third and fourthposited in the hopper 12 and be adapted to' The material fed to tanks Aand G contains about 5% of solids or less in the case of very finematerials. The material fed to this tank effects a very complete removalof thecolloids because of such dilution and because of the comparativelysmall amount of colloid material present.

As a general rule belts intended to wlthdraw precipitated colloids mustbe run slower than is necessary for similar belts for removingcrystalloids to avoid eddles which otherwise would keep the colloids insuspension. 0

Generally stated the process may be said to consist of separating thecolloids and crystalloids by taking advantage of the early portion ofthe settling cycle in a diluted slime solution or in other wordsprecipitating a portion of the crystalloids before the colloids canassume their flocculent arrangement, precipitating the balance of thecrystalloids through the flocculent colloids while the same. aresufliciently separated as not to obstruct the descent of thecrystalloids, and then removing the colloids before they can settle inany large amount.

Having thus described the invention, what I claim is 1. The art ofseparating crystalloids from slimes which tend to become flocculent,which consists in diluting the slime mixture sufficiently to insure theexistence of spaces between the flakes for the passage of thecrystalloid particles, allowing said particles to settle through saidspaces and removing said flakes .while in suspension from the settlingzone 'and prior to the precipitation of any substantial portion thereof.

2. The art of separating crystalloids from slimes which tend to becomeflocculent,

which consists in diluting-the slime mixture sufficiently to insure theexistence of spaces between the flakes for the passage of thecrystalloid particles, holding said diluted mixture in a shallow depthor layer and allowing said particles to settle through said spaces,whereby interference by the flakes with the settling of the particles isminimized, and removing the flakes while in suspension from the settlingzone and prior to the precipitation of any substantial portion thereof.x

3. The art of separating crystalloids from slimes which tend to becomeflocculent, which consists in diluting the slime mixture sufliciently toinsure the existence of spaces between the flakes for the passage of thecrystalloid particles, and producing a slow whole flow of the dilutedmixture in a shallow stream permitting the settling of said particlesthrough said flakes while carrying substantially all said flakes insuspension beyond the zone of precipitation of said particles.

4. The art of separatlng crystalloids from 'slimes which tend to becomeflocculent,

which consists in diluting the slime mixture sufficiently to insure theexistence of spaces 7 between the forming and settling flakes for thepassage of the crystalloid particles, holding said diluted mixture in ashallow depth or layer and allowing said particles to settle throughsaid mixture prior to and during the formation of said flakes, andremoving said'flakes while in suspension from the settling zone andprior to the precipitation of any substantial portion thereof.

6. The art of separating crystalloids from -slimes which tend to becomeflocculent,

which consists in diluting the slime mixture sufficiently to insure theexistence of spaces between the forming and settling flakes for thepassage of the crystalloid particles, and,

producing a slow whole flow of the diluted mixture in a shallow streampermitting the settling of said particles through said mixture prior toand during the formation of said flakes while carrying substantially allsaid flakes in suspension beyond the zone of precipitation-of saidparticles.

7. The method of separating crystalloids from colloids in slimesolutions which consists in producing a free settling condition bydilution of the slimes with water; then causing a continuoussubstantially horizontal flow of such mixture in a shallow andsubstantially'uniform stream across the bottom of a tank whereby thecrystalloids and the colloids are successively "deposited in the flowacross the tank; removing from the tank the precipitates containingsubstantial proportions of crystalloids; and then finally greatlydiluting said precipitates with water and subjecting this more dilutedmixture to a repetition of the treatment above outlined in a second andsimilar tank to remove any colloids not removed in the first treatment.

8. The method of separating crystalloids from colloids in slimesolutions which consists in producing a free settling condition bydilution of the slimes with water; then causing a continuoussubstantially horizontal flow of such mixture in a shallow andsubstantially uniform stream across the bottom of a, tank whereby thecrystalloids and the colloids are successively deposited in ,-the flowacross the tank and clear water is In testimony whereof I have signed myname to this specification in the presence of two subscribing Witnesses.

. DAVID COLE. Witnesses:

L. T. PAYNE, W. J. LANSING.

